The present invention relates in general to the field of veneer processing, and in particular to a new and useful machine and method for trimming the longitudinal edges of a stack of veneers, the machine and method being associated with a device for determining or applying at least one lengthwise cutting or reference line on the stack.
Machines of this kind are known in various designs. The device for determining the cutting line is usually located in the cutting area. The cutting line is determined with the aid of a so-called director light which falls on the surface of the top veneer of the stack. This line of light permits the determination of where the stack edge is to be cut. The cutting line will primarily be determined by the contour of the edge. It must extend so as to trim the stack over the entire length thereof and obtain a neat edge on every veneer. Care must be taken in addition to cut away knots or other defects in a marginal zone of the veneer. If the director light is placed so as to determine the cutting line directly by the line of light, the cutting operation can be started instantly. The same applies to cuts which may be needed in the transverse direction. During the cutting operation, the veneer stack is placed on a truck or another carriage, with which it is moved under the director light until the light marks the correct line.
After the first trimming operation, the stack is retracted, removed from the truck, turned through 180.degree., and again placed on the truck for displacement in the direction of the cutting plane, for determining the second cutting line, and effecting the second cutting operation.
Another prior art machine of this kind operates in a similar way, only the reference light is not in the cutting area, it is provided between the cutting area and the operator. Upon determining the first, lengthwise cutting line, a stop is set. The truck is then moved in the direction of the cutting plane until another stop butts against the set stop. The cutting line is thereby brought into coincidence with the cutting plane, and the cutting operation may start without further checking.
With this machine also, the stack must be retracted, turned, and again advanced to perform the second cutting operation. This turning, which is effected manually, involves the risk that the individual veneers will be displaced relative to adjacent ones in the stack, and then cut to a different size. Further, it may happen that one or even a plurality of displaced veneers will not have a neatly cut edge. Even veneers with non-parallel edges may thus be produced.